The Federation had discovered holographic tech 100 years before Discovery is set so it’s not that hard to believe. The show is set around the year 2250 and that is right around the time when the Federation started using Holographic projection, Discovery being a brand new prototype ship, it makes sense.

Vulcan terrorists a new idea? Nope, see TNG and DS9. Also, the federation already had holographic technology for 100 years before Discovery is set, sure holodecks didn’t exist yet but they did have recreation rooms that used holographic tech.